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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 34 |
| 5 | 120 |
| 6 | 483 |
| 7 | 1882 |
| 8 | 7858 |
| 9 | 32229 |
| 10 | 138321 |
| 11 | 585584 |
| 12 | 2560197 |
| 13 | 11082844 |
| 14 | 49100853 |
| 15 | 215982063 |
| 16 | 966695396 |
| 17 | 4303305428 |
| 18 | 19415733580 |
| 19 | 87237177735 |
| 20 | 396131418000 |
| 21 | 1793098913907 |
| 22 | 8185259827903 |
| 23 | 37274332989985 |
| 24 | 170905371225916 |
| 25 | 782158684200893 |
| 26 | 3599711338887352 |
| 27 | 16543367154806041 |
[1,1,3,9,34,120,483,1882,7858,32229,138321,585584, 2560197,11082844,49100853,215982063,966695396, 4303305428,19415733580,87237177735,396131418000, 1793098913907,8185259827903,37274332989985, 170905371225916,782158684200893,3599711338887352, 16543367154806041] |